FXUS64 KHGX 020555
AFDHGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1155 PM CST TUE DEC 1 2009
.AVIATION...
TAF SITES CEILINGS DROPPING TO IFR BEHIND ONCE WINDS SHIFT TO WEST
ACROSS CWFA. VISIBILITIES ANTICIPATED TO GRADUALLY DECREASE BUT
REMAINING MAINLY 3 TO 5 MILES IN FOG TOWARD MORNING EXCEPT
POSSIBLY LOWER LBX AND CXO. WEST WINDS INCREASING AFTER SUNRISE.
CEILINGS SHOULD LIFT BY MID MORNING TO MVFR. 37
&&
.PREV DISCUSSION... /ISSUED 920 PM CST TUE DEC 1 2009/
DISCUSSION...
WATER VAPOR IMAGERY SHOWS THE UPPER LOW NEAR DEL RIO THIS HOUR.
LARGE SWATH OF STRATIFORM RAIN ASSOCIATED WITH THE LIFT AHEAD OF
THE UPPER LOW COVERS THE CWA THIS HOUR. SOME ISOLATED THUNDER
COULD STILL AFFECT THE COASTAL COUNTIES. RAINFALL AMOUNTS AVERAGING
1/2 TO 1 INCH WITH SOME ISOLATED TOTALS 1 TO 2 INCHES. THE BULK OF
THE PRECIPITATION SHOULD BE OUT OF THE AREA BY MIDNIGHT...BUT WILL
HOLD ONTO SOME SLIGHT CHANCE/CHANCE POPS EASTERN HALF AFTER
MIDNIGHT. AS DRY SLOT SPREADS INTO THE AREA SOME PARTIAL CLEARING
COULD TAKE PLACE LATE TONIGHT OVER THE WESTERN ZONES...SO WILL SEE
COOLEST TEMPS THERE. WRAP-AROUND LOW CLOUDS SHOULD FILL AREA WIDE BY
MORNING...WITH A FEW SHOWERS STILL POSSIBLE UP NORTH. PORTS DATA
INDICATE THAT TIDE LEVELS ARE ON A DOWNWARD TREND...WITH PLEASURE
PIER DOWN TO 3.0 FEET AND PIER 21 DOWN TO 3.2 FEET. AS A
RESULT...HAVE LET THE COASTAL FLOOD ADVISORY EXPIRE AS OF 9 PM.
LOOKING AHEAD TO FRIDAY'S EVENT IN WHICH EACH MODEL RUN IS BEING
HEAVILY SCRUTINIZED. THE NEW 00Z NAM IS A BIT SLOWER WITH THE
UPPER LOW AND DELAYS ONSET OF PRECIP UNTIL FRIDAY AFTERNOON.
NAM FCST SOUNDINGS STILL SUPPORT SNOW FOR THE NORTHERN ZONES AND
A MIX OF RAIN AND SNOW FOR THE HOUSTON AREA LATE IN THE DAY
LASTING INTO THE EVENING HOURS. IT SHOULD BE POINTED OUT THAT
CLIMATOLOGICALLY...HOUSTON HAS NEVER SEEN MEASURABLE SNOW OCCUR ON
TWO CONSECUTIVE WINTER SEASONS.
35
PREV DISCUSSION... /ISSUED 538 PM CST TUE DEC 1 2009/
AVIATION...
WIDESPREAD RAIN WITH EMBEDDED SHOWERS MOVING OVER CWFA EARLY THIS EVENING.
AHEAD OF UPPER LOW OVER THE TRANS-PECOS. WE INDICATED IFR CEILINGS
WITH MVFR VISIBILITIES IN MAINLY LIGHT RAIN BUT TEMPO LIFR CEILINGS
AND IFR VISIBILITIES WITH PASSING EMBEDDED SHOWERS. THIS WILL BE MAINLY
DURING THE EVENING HOURS. CEILINGS NOT ANTICIPATED TO LIFT UNTIL
TOMORROW MORNING. RAIN COVERAGE SHOULD DIMINISH RAPIDLY AFTER MIDNIGHT
WEST TO EAST. 37
PREV DISCUSSION... /ISSUED 317 PM CST TUE DEC 1 2009/
DISCUSSION...
A STRONG CLOSED UPPER LEVEL LOW CONTINUES TO PUSH ACROSS THE BIG
BEND AND INTO W TX THIS AFTERNOON. SFC ANALYSIS DEPICTS A COASTAL
LOW PRESSURE OFF THE TX GULF COAST. THE COASTAL LOW WILL HELP
MAINTAIN EASTERLY WINDS WHICH WILL TURN MORE TO THE NORTH
OVERNIGHT. THIS SHOULD BRING AN END TO ANY COASTAL FLOODING
ISSUES. THE CLOSED LOW SHOULD PUSH ACROSS TX TONIGHT WITH ANOTHER
ROUND OF MODERATE RAIN ON ITS WAY. REGIONAL RADARS SHOW THIS RAIN
OVER MUCH OF W C TX AND C TX. ITS EASTERN EDGE IS JUST STARTING
TO REACH SE TX. RAIN WILL PASS THROUGH SE TX MAINLY BETWEEN 00Z
AND 06Z WED WITH RAIN TAPERING OFF AFTER 06Z. SOME LINGERING RAIN
WILL BE POSSIBLE INTO WED MORNING BUT DRIER CONDITIONS ARE
EXPECTED WED AFTERNOON.
12Z 500MB ANALYSIS ALONG WITH WATER VAPOR IMAGERY SHOW THE NEXT
SHORTWAVE TO AFFECT SE TX IN THE PAC NW. THIS WAVE PASSES THROUGH
THE ROCKIES RATHER SLOWLY OVER THE NEXT COUPLE OF DAYS UNTIL A
110KT JET STREAK AT 300MB PUSHES INTO THE SHORTWAVE THU NIGHT.
THIS SHORTWAVE THEN SWINGS ACROSS TX INTO SE TX BY 00Z SAT. THE
NAM/GFS SOLUTIONS ARE IN FAIRLY DECENT AGREEMENT ALTHOUGH THE
MAIN PROBLEM OVER THE NEXT COUPLE OF DAYS WILL BE THE TIMING OF
THIS FEATURE AND WHETHER IT SPEEDS UP OR SLOWS DOWN. AS THE
SHORTWAVE MOVES ACROSS THE AREA...STRONG COLD ADVECTION OCCURS
ALLOWING FOR FALLING TEMPERATURES DURING THE DAY. TEMPS AT 850MB
DROP BELOW FREEZING DURING THIS TIME. LOOKING AT MOISTURE FIELDS
AND FORCING...IT LOOKS LIKE PRECIPITATION WILL LIKELY START AS
RAIN DURING THE MORNING AND CHANGE OVER TO SNOW DURING THE DAY ON
FRIDAY AS TEMPERATURES DROP. THIS IS ALL DUE TO THE SHORTWAVE
TROUGH MOVING OVER THE REGION WITH STRONG QG LIFT. FRONTOGENESIS
INCREASES DURING THE DAY MAINLY IN THE MID LEVELS. THE NAM IS
STRONGER THAN THE GFS WITH THE FORCING AND SUPPORTS BANDED
PRECIPITATION OVER THE REGION. STILL BOTH MODELS SHOW A
TRANSITION OF RAIN TO SNOW IN THE MODEL SOUNDING DATA AS FAR
SOUTH AS KHOU. GENERALLY THINK AREAS NORTH OF I-10 WILL SEE A
COMPLETE TRANSITION WITH AREAS SOUTH OF I-10 SEEING A MIX OF
RAIN/SNOW. AGAIN A LOT OF THE FORECAST DETAILS HINGE ON THE
TIMING OF THE SHORTWAVE TROUGH AS WELL AS HOW MUCH MOIST COLD AIR
WILL BE AVAILABLE IN THE LOWER LEVELS. POPS WERE INCREASED TO 40
PERCENT AREA WIDE BUT COULD SEE HIGHER CHANCES SHOULD THE MODELS
BEGIN TO KEY ON A SPECIFIC AREA FOR RAIN/SNOW. SNOW ACCUMULATIONS
ARE DIFFICULT TO DETERMINE AT THIS TIME BUT SHOULD THE MODELS
CONTINUE WITH THESE TRENDS...THERE MAY BE THE THREAT OF ENOUGH
SNOW ACCUMULATION TO WARRANT A WINTER WEATHER WATCH/WARNING. A
SPECIAL WEATHER STATEMENT (SPS) WILL BE ISSUED TO HANDLE MORE
DETAILS AND PROVIDE UPDATES AS FORECASTERS MONITOR THIS
DEVELOPING WINTER WEATHER SCENARIO.
THE SYSTEM SHOULD BE FAST MOVING SO ANY RAIN/SNOW SHOULD BE OUT
OF SE TX FRI NIGHT. ANOTHER WEAK SHORTWAVE IN THE STRONG ZONAL
FLOW ON SUNDAY WILL PROVIDE ENOUGH LIFT FOR A ROUND OF SHOWERS.
POPS WERE INCREASED TO 30 PERCENT FOR SUNDAY WITH DRIER
CONDITIONS ON MONDAY. GIVEN A RATHER PROGRESSIVE PATTERN WITH
SHORT WAVE TROUGHS AND JET STREAKS PROPAGATING THROUGH THE
FLOW...WILL MAINTAIN 20 POPS FOR ALL OF EARLY NEXT WEEK. THIS
WILL MAINLY BE DUE TO SHOWERS DEVELOPING WITH ANY WARM
ADVECTION/ISENTROPIC LIFT SITUATIONS THAT DEVELOP. TEMPERATURES
DO MODERATE EARLY NEXT WEEK BUT WILL STILL RUN BELOW NORMAL FOR
THE WEEKEND.
39/OVERPECK
AVIATION...
MESSY TAFS ON TAP WITH PERIODS OF RAIN AND FOG. EXPECT LOW CIGS
OVERNIGHT WITH SOME IMPROVEMENT BETWEEN 06-12Z. CLOUDS SLOW TO
CLEAR DURING THE DAY WITH WRAP AROUND CLOUDS/MOISTURE KEEPING
NORTHERN TAF SITES CLOUDY WITH SOME PARTIAL CLEARING OVER
SOUTHERN TAF SITES. 43
MARINE...
LOW PRESSURE OVER THE WESTERN GULF OF MEXICO WILL PUSH EAST
NORTHEAST THIS EVENING AND AWAY FROM TEXAS COAST. EAST TO
NORTHEAST WINDS WILL BACK TO THE NORTH AND NORTHWEST OVERNIGHT.
TIDE LEVELS ARE RUNNING 1.5 FEET ABOVE NORMAL AND COULD RISE A
BIT MORE BEFORE LEVELING OFF AS THE WINDS BECOME NORTHWEST. WILL
MAINTAIN THE COASTAL FLOOD ADVISORY THROUGH 9 PM. WILL ALSO
MAINTAIN THE SCA AS WINDS AND SEAS REMAIN ON THE HIGH SIDE. WINDS
WILL BRIEFLY DROP OFF ON THURSDAY ONLY TO INCREASE AGAIN LATE
THURSDAY NIGHT INTO FRIDAY. VERY STRONG COLD AIR ADVECTION OVER
THE WARMER WATERS WILL BRING WIND SPEEDS UP QUICKLY. WOULD NOT BE
SHOCKED IF SEAS OF 10-12 FEET DEVELOP. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 40 54 35 54 37 / 100 20 10 10 20
HOUSTON (IAH) 44 56 37 56 41 / 100 10 10 10 20
GALVESTON (GLS) 48 58 43 58 46 / 100 10 10 10 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL 4 AM CST WEDNESDAY FOR
THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY.
SMALL CRAFT ADVISORY UNTIL 6 AM CST THURSDAY FOR THE FOLLOWING
ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL
20 NM TO 60 NM...WATERS FROM FREEPORT TO THE MATAGORDA SHIP
CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20
TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM.
&&
$$
